It is known to provide a fuel injector with an external filter means disposed to filter the fuel before it enters the fuel inlet of the injector. Whilst such a filter can prevent particulate material in the fuel from entering the fuel injector, it is incapable of protecting the valve means of the fuel injector from damage or blockage by particulate material that may originate internally of the fuel injector, either due to processes used to manufacture and assemble the fuel injector or due to usage.
Accordingly, it is desirable to provide filter means within the fuel injector, downstream of the fuel inlet and upstream of the valve means thereof. However, internal filter means have not been successfully used due to the limited available space within the fuel injector body for the provision of filters and the requirement that filters should not affect the normal operation of the fuel injector by causing excessive restriction to the flow of fuel with the injector or by interfering with the moving parts of the fuel injector, in particular the pintle.